Intrinsically Switchable and Bandwidth Reconfigurable FBAR Filter Employing Electrostriction in Ferroelectric BST

Innovative, reconfigurable frequency selective microwave components are essential to reduce the expanding transceiver systems' complexity, size, and cost. This paper presents for an intrinsically switchable and bandwidth (BW) reconfigurable FBAR filter by using the electrostriction effect in ferroelectric barium strontium titanate (BST). A BW switchable filter is designed, fabricated, and characterized. Under the application of DC bias voltage, the filter exhibits a bandpass response with a fractional bandwidth (FBW) of 3%. Changing the DC bias configuration adjusts the overall transfer function of the filter, transitioning into a secondary state with a FBW of 2.2%. Without any bias however, the filter switches off and provides an isolation greater than 12 dB.